Rolling seal devices and diaphragms



April v25, 1967 J, F, TAPUN 3,31s,s72

ROLLING SEAL DEVICES AND DIAPHRAGMS Filed March 8 1965 2 vSh -:-et,s-Shee'f. 2 V

United States Patent Office.

3,3 15,5 72 Patented Apr. 25, 1967 3,3l5,572 ROLLING SEAL DEVICES AND DIAPHRAGMS John F. Taplin, 15 Sewall St., West Newton, Mass. 02165 Filed Mar. 8, 1965, Ser. No. 437,844 6 Clams. '(Cl. 92-99) This inventon relates to rolling seal diaphragm devices and diaphragms.

I have discovered an important novel rolling seal diaphragm bistable in top hat configuration (as shown in FIG. 6) and in one convoluted configuration, that not only further reduces wear owing to reduction of convolution stresses but facilitates nested shipping (in the top hat configuration). I provide in a preferred embodiment a diaphragm with a wall defined by revolution about an axis of a line including a pair of arcs of radii extending from opposite sides of the line; the arcs may merge into each other, or they may be spaoed, as by a straight line to which both are tangent.

Other features, objects, and advantages of the inven- -tion will appear from the following description of a preferred embodiment, in which:

FIG. 1 is a diagrammatic view of a roHing seal diaphragm device;

FIGS. 2a, 2b, Zc, and 3 are corresponding diagrammatic views illustrating the effect of relative movement of piston and housing;

FIG. 4 is a vertical sectional view at 4-4 of FIG. 5;

FIG. 5 is a sectional view at 5-5 of FIG. 4;

FIG. 6 is a vertical sectional4 view of the unconvoluted rolling seal diaphragm shown in FIG. 4; and

FIG. 7 is a partial, enlarged view, showing the initially snap-convoluble portion of the diaphragm of FIG. 6.

Referring now in 'greater detail to the drawings, there is shown in FIG. l a conical housing 10 and a conical piston 12, each defined by revolution, about a common vertical axis, of lines at 45 to the axs and at 90 to each other, with rolling seal diaphragm 14 convoluted therebetween to subtend an are corresponding to said 90.

The diaphragm preferably should be formed in manufacture with its inner surface of a configuration conforming, at least in part, to the outer configuration of the piston, making buckling in compression of at least this part (which in some embodirnents may be most or almost all of the rolling wall) impossible in use. Although the diaphragm 14 is diagrammatically shown in FIG. 6, it actually includes a circumferentially compressed layer of fabric with interlocking fibers (woven or knitted), through the interstices of which have been forced an elastomer, all as described in detail in various aspects in my United States Patents Nos. 2,849,026, 3,083,734, and 3,l37,215.

In the preferred embodimnet shown, the fabric element is formed to the configuration shown by the upper and lower dotted lines of FIG. 6, taken with the intermediate solid lines into which the dotted lines merge. Then the fabric element (for example, of woven polyester) and elastomer (for example, acrylontrile) are united, still retaining this same shape, and cured about 90% in a first mold having the configuration of the lower dotted lines of FIG. 6 and the solid lines thereabove into Which said dotted lines merg In completing the cure, the unit is formed between dies that impose on it its final convoluted stable configuration, as shown in FIG. 6, taking the dotted upper portion together with the solid lower portion 36 into which it merges. The resultant diaphragm is stable in both the final top hat configuration of the solid linesV of FIG. 6 and the final convoluted stable configuration referred to.

I detailed view of portion 38 of diaphragm 14 shown in FIG. 7. As will be seen, this portion is symmetn'cal about a reversely curved centerline defined by a pair of arcs ofL radii r (the radius of convolution of the diaphra-gm) of the same length (9 is the angle between thev aXis of the diaphragm and the radius r perpendicular to the surface of the piston 12 and housing 10), struck from centers on opposite sides of the wall, the arcs being of the same length and flowing into each other at a tangent to both. Furthermore, the head corner radius 50 is formed in its stable top hat configuration in the first molding step, but in its (reverse) stable convoluted configuration in the second molding step, as shown. This diaphragm may be snapped into convoluted form by an unskilled Worker, even thought unassembled to a piston or cylinder. It is bistable: that is, the diaphragm rests without outside application on it of any force, and rela- I tively stress-free, in either top hat or stable convoluted configuration.

The reduction of stress owing to the very fact of convolution is itself an important factor in increasing flexlife, and an important feature of the novel diaphragm. From this standpoint either the intermediate portions or the head corner radius, contribution is significant, aside from the other, but for best results the diaphragm should be manufactured so as to have the benefiit of their joint contribution.

Stability in a convoluted position into which an unskilled assembly line Worker can snap the diaphragm facilitates shipment of diaphragms separately, and in inexpensive nesting top hat configuration if desired, which is also of considerable practical importance. In preferred embodiments the rolling wall is tapered, say 6, for this nestability, although the bistable character is of course important wholly aside from nestability.

Other embodiments than that shown will occur to those skilled in the art.

I claim:

1. A rolling seal .diaphragm with a rolling wall including a longtudinally intermediate portion with a centerline inluding a pair of arcs of the same length and of radii of the same length, the radii being struck from centers on opposite sides of said wall.

2. The rolling seal diaphragm of claim 1 Which is convolubly bistalble around a head corner radius thereof.

3. The diaphragm of claim 1 in which said rolling wall is conical above and b'elow said intermediate portion.

4. The diaphragm of claim 1 in which said arcs merge into each other along a tangent to both.

5. A rolling seal diaphragm device comprising a housing with a housing diaphragm support surface, a piston With a piston diaphragm support surface mounted for longitudinal movement in said housing, and a rolling seal diaphragm convoluted and secured around housing and piston ends respectively by said housing and said piston, said housing daphragm support surface and said piston diaphragm support surface being defined by rotating a first and a second line respectively about a common longitudinal axis, said first line and said second line being each straight lines converging as extended in an acute angle in the direction that the radius of convolution of said diaphragm extends from the center of said radius to said convolution, at least a portion of the mating surfaces of said diaphragm and said piston being in fitting relation therearound while said diaphragm is unstressed around said portion, and said rolling seal diaphragm being bistable, having stability without stress in both top hat and convoluted configurations by virtue of an unconvoluted configuration in which the diaphragm rolling'wall includes a longitudinally intermediate pori tion having a centerline including a pair of arcs of the sam'e length and of radii of the same length, said radii V being struck from centers on opposite sides'V of said Wall and said arcs imerging intoV each other along va tangent to both, each said arc having a length half the 'arc length of said convolution, said radii being of .the same' length as said radius, saidrkdiaphragm being convolubly bistable i around a head corner radius thereof.

6. A rolling. seal diaphragm device comprising a housing With Va housing diaphragm support surface, a pistonL WithV a piston diaphragm support surface mounted for ing a longitudinally intermediate portionV witha center line including a pair of arcs of the same length and of lters on opposite sides i i diaphragm support surface and said piston support sur- V radii of the same length, the radii being struck from cenof said Wall, 'andV said housing an acute angle in -the direction that the radius of convolution of said diaphragm extends from the center of said radius to said convolution,

second lines defining an angle of at least 10 With Vsaid 1 References Cted bythe Examineri v UNITED STATES PATENTS i* 971,5sa 10/1910 Ben 92-9 1,716,200 6/1929 Wilson V92+99l V2,689,586 9/1954 Anderson 92-f-99X MARTIN P. SCHWADRON, Primaly Eacaminer. I. C. COHEN, Assistant Examiner.

and each of asid firstV andL 

1. A ROLLING SEAL DIAPHRAGM WITH A ROLLING WALL INCLUDING A LONGITUDINALLY INTERMEDIATE PORTION WITH A CENTERLINE INCLUDING A PAIR OF ARCS OF THE SAME LENGTH AND OF RADII OF THE SAME LENGTH, THE RADII BEING STRUCK FROM CENTERS ON OPPOSITE SIDES OF SAID WALL. 